Solutions to Improve Picking Quality for EDEKA Südwest

Problem Space

You will find all information regarding the business problem and context of the project.

Context

The logistics center processes a large and diverse assortment of over 30,000 SKUs (non-cooled), which are picked daily across multiple warehouse zones and consolidated into roll containers for store delivery. Order picking in the logistics center is currently carried out using a pick-by-voice system which guides workers through the aisles.

Outbound quality checks reveal that the error rates have been rising continuously over the last years. As a result, overall picking quality is declining, and EDEKA Südwest is looking for a solution that can monitor and sustainably improve the picking quality of workers.

Problem Definition

Internal outbound sampling suggests a relatively low overall error rate, while store-level complaint data points to a noticeably higher real-world error rate. Although the error rate may appear minor at first glance, it becomes highly significant when viewed at the scale of a high-volume logistics operation.

The central issue is that picking mistakes often go unnoticed at the moment they occur and become visible only downstream. The main error types are well-known:

Wrong quantity
Workers pick too many or too few units/ collies compared to the order specification.
Wrong item
The picker selects the incorrect article — often due to similar packaging, close shelf placement, or fast movement.
Wrong roll container
Items/ collies are picked correctly in the aisle but end up on the wrong container e.g. because container switches are not consistently confirmed.

Why it happens:

No immediate error detection: Workers receive no simple, low-friction indication when they place an item on the wrong container or pick the wrong quantity.
Limited traceability: It is difficult to reconstruct picking actions or container switches, which complicates root-cause analysis and process improvement.
Behavioral drivers: Under time pressure, optional confirmation steps are skipped, making human factors a relevant contributor to recurring errors.
Downstream consequences: Errors lead to missing or excess items in stores, store-level complaints, replacement processes, and additional handling costs.

Central Warehouse in Rastatt:

The new central warehouse in Rastatt handles up to 90 inbound and 90 outbound trucks per day, with space for over 31,000 pallets, extensive automation, and around 400 employees supporting operations. Since its launch, it has become the operational and strategic heart of the logistics network, supplying five regional distribution centers with dry goods such as coffee, snacks, and canned products, which are then delivered to EDEKA stores.

Below you will find more information about the central warehouse in Rastatt:

System specifications:

These are the systems currently used by EDEKA Südwest:

Warehouse/order management system: Wamas from SSI Schäfer
Pick-by-voice system: LYDIA Voice from the Ehrhardt Partner Group (EPG)

Picking Process with LYDIA

In the current setup, the picking process is guided by the voice-based system LYDIA, which supports operators step by step throughout the entire workflow. In addition, EDEKA Südwest expects to introduce an extension of LYDIA with a display for additional information in Q1, providing further visual guidance and feedback to the operators. The process is structured as follows:

Position Instruction: LYDIA communicates the exact picking location to the operator via headset, including the color of the control digit attached to the rack from which the items must be taken.
Position Confirmation by the Operator: Upon reaching the shelf, the operator speaks out the control digit in the corresponding color. The system verifies whether the correct picking location and article have been reached.
Quantity Instruction: LYDIA specifies the exact number of packages (colli) to be picked.
Picking and Quantity Confirmation: The operator removes the indicated number of packages and verbally confirms the picked quantity to the system.
System Quantity Check: LYDIA validates the stated quantity for correctness.
Process Repetition: This sequence is repeated until all items of the current order have been completely picked.

This voice-guided interaction enables hands-free operation and high throughput. At the same time, it depends on accurate execution and confirmation by the operator at each step, making the process sensitive to human error under time pressure.

To provide a better understanding of the physical environment and the complexity of the task, images of typical warehouse locations and shelves are integrated below. These visuals illustrate the structure of the storage areas, the labeling of picking locations, and the real-world conditions in which operators perform their work.